Thermostabilizer for extracorporeal oxygenator



March 19, 1968 w. E. FARRANT THERMOSTABILIZER FOR EXTRACORPOREAL OXYGENATOR 2 Sheets-Sheet l Filed June 15 FIG. 1.

F'l G 2 FIG 3 lNVENTOR WILLIAM E. FARRANT ATTORNEYS March 19, 1968 w. E. FARRANT 3,374,066

THERMOSTABILIZER FOR EXTRACORPOREAL OXYGENATOR Filed June 15, 1964 2 Sheets-Sheet 2 lNVENTOR WILLIAM E. FARRANT AT TO/PNEVS United States Patent Ofifice 3,374,066 THERMOSTABILIZER FOR EXTRACURPOREAL OXYGENATOR William E. Farrant, 5224 St. Antoine,

Detroit, Mich. 48202 Filed June 15, 1964, Ser. No. 375,236 Claims. (Cl. 23-2585) This invention relates to the combination in an oxygenator and particularly a blood tube communicating with the oxygenator of a thermostabilizer adapted to heat the blood passing through the tube to the desired temperature.

It also relates to apparatus as hereinabove described wherein the thermostabilizer is so disposed within the oxygenator system that the tendency to produce air bubbles in the blood passing through the thermostabilizer and through the system is minimized so that such air bubbles will not enter into the blood stream of the patient.

Another object is the provision of a thermostabilizer of the character set forth which can be coupled into a blood tube communicating with the oxygenator and with the patient so as to control the temperature of the blood passing through the thermostabilizer and to do this without increasing the quantity of the blood in the oxygenator system. In other words the addition of the thermostabilizer to the oxygenator system does not add blood capacity to the volume over that provided originally with the oxygenator system.

In the utilization of an oxygenator in open heart surgery the amount of blood required for the patient obviously varies substantially depending upon whether the patient is a large adult or a small child, and as will be apparent there are different volumes required between the maximum and minimum extremes.

My invention does not relate to the oxygenator system as such but is usable with conventional oxygenator systems currently on the market.

In such oxygenator systems there is a portion adapted to serve the purpose of the lungs of the patient and add oxygen to the blood and withdraw CO therefrom and there is means provided to pump the blood when the blood tubes communicate with the proper venous and arterial structures in the body of the patient being operated upon.

My invention relates to the provision of a suitable thermostabilizer or heat exchanger means which is coupled up in this oxygenator system to control the temperature of the blood. As also hereinabove indicated rny thermostabilizer is also so coupled in the oxygenator system that if any bubbles were created in the heating of the blood such would be removed because the thermostabilizer is disposed in the venous line and the blood flowing the-rethrough then goes through the debubbling chamber.

Another object is the provision of a thermostabilizer of the character set forth in which the blood conduit portion, or that portion through which the blood flows, as distinguished from the heat exchange portion may be readily disassembled from the heat exchange portion and thrown away after each operation and a new blood conduit portion installed.

Other objects and advantages will more fully appear from the following description, drawings, and claims, herein:

In the drawings, FIG. 1 is a diagrammatic illustration of an oxygenator in common use put out by Travenol Laboratories and my thermostabilize'r is installed in one of the blood tubes communicating between this oxygenator and a patient;

FIG. 2 is a longitudinal cross sectional view through one embodiment of my thermostabilizer;

3,374,066 Patented Mar. 19, 1968 FIG. 3 is a transverse sectional view taken on line 3-3 of FIG. 2;

FIG. 4 is a fragmentary sectional view through an end portion of one embodiment of my thermostabilizer;

FIG. 5 is a longitudinal sectional view through a fragment of an end portion of the blood conduit part of another embodiment of my thermosta'bilizer;

FIG. 6 is a transverse cross sectional view through the blood conduit portion of one modification of my thermostabilizer;

FIG. 7 is a transverse cross sectional view similar to FIG. 6 showing a modification thereof;

FIG. 8 is a transverse cross sectional view through a blood conduit showing another modification thereof;

FIG. 9 is a transverse cross sectional view through the embodiment of my blood conduit shown in FIG. 5;

FIG. 10 is a longitudinal fragmentary cross sectional view through the heat exchange portion adapted to be associated with the blood conduit portions shown in FIGS. 5 and 9; and

FIG. 11 is a transverse sectional view taken on the line 1111 of FIG. 10.

In FIG. 1, as hereinabove stated there is shown schematically an oxygenator of Well known form adapted to be coupled up with a patient shown disposed on a table, except that the oxygenator system includes my improved thermostabilizer identified by the numeral 20. This thermosta bilizer is coupled into the venous line 22 which is adapted to be connected with the venae cavae of the patient. This line leads to an oxygen column 24 of the oxygenator which in turn communicates with a debubbling chamber 26. This debubbling chamber is provided with vents 28 for CO and excess oxygen and there are portions of the oxygenator which terminate in an arterial line 30 that is provided with a pump 32 and which line communicates with the desired arterial portion of the body of the patient. Pumps 34 and 36 are shown in two lines 38 and ll), which lead to a cardiotomy reservoir 42. All of the hereinabove described apparatus is standard and forms no part of my invention. It merely establishes the environment within which my invention is disposed.

My invention has to do with the thermostabilizer or heat exchanger indicated geenrally in the schematic drawing of FIG. 1 by the numeral 20. This thermostabilizer may take different forms and several difiFerent modifications are shown herein. In FIGS. v2 and 3 there is shown a thermostabilizer which comprises a blood conduit portion 44 surrounded by heat exchange portion 46. The. blood conduit portion is illustrated as comprising a blood conduit which may be formed of metal or other satisfactory heat conducting material. This metal tube would have its inner surface, which is exposed to the blood, siliconized as is well known.

This blood conduit portion is disposed within the water carrying tubular portion 46 which might be formed of plastic or any suitable material. The outer tubular portion 46 is shown in FIG. 2 as formed of lower and upper sections 46A and 46-B respectively for ease in assembly over the blood conduit portion. These two sections of the water tube are secured together by a clamping device 48 which is provided with an adjustable support 50 whereby it may be supported from any suitable frame or table and adjusted as desired.

The water tube has an inlet 52 and an outlet 54 whereby water at the desired temperature may be caused to flow through the tube. It is shown herein as flowing counter the flow of blood through the blood conduit. The blood a conduit 44 is shown as having upper and lower end portions 56 and 58 respectively secured to the conduit and adapted to be connected with the blood tube 22 of the oxygenator. The ends of the water tube are provided with threaded end caps 60 adapted to tighten the ends of the water tube about the ends of the blood tube as shown. Suitable packing elements 62 are also provided.

The oxygenator system is provided with blood tubes 30 and 22 of sufiicient length to provide sufiicient blood capacity to accommodate patients of different size and such tubes may be cut to the length desired for the particular patient. I prefer to install my thermostabilizer in the venous line of the oxygenator system because if there are any bubbles produced due to the heating of the blood such bubbles will be removed in the debubbling chamber 26. In order that the thermostabilizer does not add to the interior cubic contents of the system and require a larger priming charge than should be employed under the particular situation, I have provided that the blood conduit 44 of the thermostabilizer will present the same interior capacity per unit of length as would be presented by the same unit of length of the blood tube 22.

In order, however, for the blood passing through the conduit to be properly heated, the inner surface of the wall of the blood conduit which is exposed to the fiow of blood is increased substantially over the inner surface of the same length of blood tube which is removed to permit installation of the conduit. It should be understood that a length of blood tube 30 is removed in order for my thermostabilizer to be inserted in the line. In other words, it is desired to heat the blood more rapidly than it would be heated were a section of blood tube merely surrounded by the heat exchange portion of the thermostabilizer.

There are many modifications or embodiments of structures that would increase the inner surface wall area ex posed to the flow of blood thereover for the same volume, and certain of these are shown in FIGS. 4 through 12 of the drawings. A feature of my improved thermostabilizer is that the blood conduit portion thereof may be readily removed from the heat exchange portion after each use'and discarded. A new blood conduit portion may be installed as a replacement. This is a highly desirable characteristic.

FIG. 4 is a fragmentary end section of one modification of blood conduit showing a plastic end Portion 64 secured to the metallic blood conduit portion 44 as the same is identified in FIG. 2, this securement may be by means of crimping as at 66, or O-rings may be used at such point. The interior of the blood conduit may be as shown in FIGS. 6 and 7, and in the sectional view of FIG. 4 one is looking at the sides of the linearly extending fins such as indicated at 68 in FIG. 6 or 70 in FIG. 7.

In FIG. 6 the blood conduit is shown as provided with eight ribs or fins which are hollow and open into the interior of the conduit. As illustrated in such figure, the entire capacity of the interior is open to the flow of blood therethrough. Due to this arrangement, there is a large inner surface Wall area that is exposed to the blood and also a large outer surface wall area that is exposed to the flow of hot water thereover.

In FIG. 7 the construction is somewhat different. There are the same number of ribs similarly disposed but the axial portion of the tube is solid and the blood flows only through the hollow ribs 70. This therefore provides a still greater capacity for heating of the blood than is indicated in FIG. 6. In both of these constructions it is understood that as illustrated in FIG. 2 there is provided an outer hot water casing within which the blood conduit is disposed and through which hot water flows to heat the blood flowing through the conduit.

In FIG. there is a modification of the construction shown in FIGS. 4, 6 and 7. In FIG. 5 the blood conduit is shown as having an end portion which resembles that in FIG. 4 but the central portion of the conduit is enlarged radially to a substantial extent and there is provided an axially disposed core-like member 72 which extends linearly through the blood conduit 74 and is held spaced therefrom by projection 76 formed on the core 4 member. A cross section of this structure in FIG. 5 is shown in FIG. 9 and it will be seen that the blood passageway 73 is relatively shallow as compared with the total inner diameter of the blood conduit 74 and the blood is caused to flow over the entire inner surface of this enlarged diameter blood conduit 74.

In the construction just above described the heating of the outer cylindrically surrounding heat exchanger may be electrical, for example, FIGS. 10 and 11 show an outer tubular element having Calrod elements 82 inserted therein to heat the same. The entire blood conduit assembly shown in FIGS. 5 and 9 would be inserted in the axial passageway 84 shown in FIGS. 10 and 11 and the end portions would seat in the tapered ends of the cored out passageway 84. Obviously the cross sectional dimensions of FIGS. 5 and 9 are enlarged over that shown in FIG. 10. It is understood of course that the opposite end portions of the blood conduit 74 would be suitably coupled with the adjacent ends of the blood tube 22 as heretofore described in connection with FIGS. 2 and 3. In order to control the temperature in this electrically heated construction the heat exchanger portion shown in FIG. 10 would be provided with a temperature sensor 86 and suitable temperature regulating means would be provided in the electrical heating support. Such, however, forms no part of this invention.

FIG. 8 shows a preferred construction wherein the blood conduit is in the form of a metal tube indicated generally as 88. Such is provided with a multiplicity of linearly projecting fins 90. The tube might be of aluminum or other suitable high conductive metal with, as hereinabove referred to, a siliconized inner surface over which the blood flows. This tube actually exhibits eight separate, somewhat generally heart-shaped passageways 92, each of which is bounded by a metal wall which defines the passageway. This blood conduit might be disposed within a hot water tubular portion such as shown in FIG. 3 wherein the blood conduit 44 is disposed within the hot water tubular portion 46.

The provision of fins 90 and the metal walls completely surrounding the blood passageways 92 provide a high quality heating surface around the blood passageways.

What I claim is:

1. In an oxygenator provided with a blood inlet tube and a blood outlet tube, a thermostabilizer having a blood conduit portion and a heat exchange portion associated with the blood conduit portion to control the temperature of the blood passing therethrough, said blood conduit portion coupled at opposite ends within one of the blood tubes of the oxygenator forming a blood passageway portion thereof, said blood conduit portion having an internal blood containing volume per unit of length equal to the internal blood containing volume per the same unit of length of the blood tube of the oxygenator within which said blood conduit portion is coupled and having an internal surface per the same unit of length and over which the blood passes therethrough substantially greater in area than the internal surface per the same unit of length of the blood tube over which the blood passes and within which said blood conduit is coupled.

2. Apparatus as defined in claim 1 characterized in that the blood conduit of the thermostabilizer is coupled in the blood inlet tube leading to the oxygenator.

3. Apparatus as defined in claim 1 characterized in that the blood conduit portion of the thermostabilizer is removably associated with the heat exchange portion thereof whereby said blood conduit portion may be removably disassociated from the heat exchange portion and replaced with another blood outlet portion.

4. In an oxygenator having a blood tube adapted to be connected with a patient to establish blood communication between the oxygenator and the patient, a thermostabilizer having a blood conduit portion and a heat exchange portion, said heat exchange portion surrounding the blood conduit portion to control the temperature of the blood passing therethrough, said blood conduit portion coupled at opposite ends within said blood tube to form a blood communicating portion of said tube, said blood conduit having an internal blood containing volume per unit of length equal to the internal blood containing volume per the same unit of length of the blood tube within which the blood conduit is coupled, said blood conduit portion being removably replaceable within the surrounding heat exchange portion of the thermostabilizer whereby it may be removed therefrom and another blood conduit portion inserted therein.

5. In a blood tube communicating with an oxygenator, a thermostabilizer comprising a blood conduit portion and a heat exchange portion associated with the blood conduit portion and adapted to control the temperature of the blood passing therethrough, said blood conduit portion coupled at opposite ends in the blood tube communicating with the oxygenator so that the blood passing through said tube also passes through said blood conduit portion, said blood conduit portion having an internal blood containing volume per unit of length equal to the internal blood containing volume per the same unit of length of the blood tube within which such blood conduit is coupled, said blood conduit portion being renewably detachable from the heat exchange portion of the thermostabilizer for replaceability.

6. In a blood conduit communicating with an oxygenator, a thermostabilizer as defined in claim 5 characterized in that the blood conduit portion thereof is disposed within a surrounding water tube through which heated water may be passed to heat the wall of the blood conduit, said wall of the blood conduit being shaped providing a multiplicity of radially projecting linearly extending rib-like portions exposed to the water passing through the surrounding water tube to heat the wall of the blood conduit portion.

7. In a blood tube communicating with the oxygenator, a thermostabilizer as defined in claim 6 characterized in that said radially projecting linearly extending riblike portions are hollow and serve as blood passageways.

8. In a blood tube communicating with an oxygenator, a thermostabilizer as defined in claim 6 characterized in that said blood conduit portion is provided with a plurality of radially disposed linearly extending individual blood passageways, each surrounded by a wall portion responsive to be heated by water passing through the water tube.

9. In a blood tube communicating with an oxygenator, a thermostabilizer having a tubular blood conduit portion and a heat exchange portion, said heat exchange portion surrounding the blood conduit to control the temperature of the blood passing therethrough, said tubular blood conduit portion being interiorly so shaped as to cause the blood passing therethrough to flow over the inner surface of the outer wall in a stream of substantially less depth than the interior diameter of the tubular blood conduit.

10. In a blood tube communicating with an oxygenator, a thermostabilizer as defined in claim 9 characterized in that the blood conduit portion is readily removed for replacement from the heat exchange portion of the thermostabilizer and said blood conduit is characterized as having an axial element disposed therein spaced from the inner surface of the wall of the blood conduit to provide a blood passageway between the axial portion and the wall of the blood conduit.

No references cited.

MORRIS O. WOLK, Primary Examiner.

BARRY S. RICHMAN, Assistant Examiner. 

1. IN AN OXYGENATOR PROVIDED WITH A BLOOD INLET TUBE AND A BLOOD OUTLET TUBE, A THERMOSTABILIZER HAVING A BLOOD CONDUIT PORTION AND A HEAT EXCHANGE PORTION ASSOCIAITED WITH THE BLOOD CONDUIT PORTION TO CONTROL THE TEMPERATURE OF THE BLOOD PASSING THERETHROUGH, SAID BLOOD CONDUIT PORTION COUPLED AT OPPOSITE ENDS WITHIN ONE OF THE BLOOD TUBES OF THE OXYGENATOR FORMING A BLOOD PASSAGEWAY PORTION THEREOF, SAID BLOOD CONDUIT PORTION HAVING AN INTERNAL BLOOD CONTAINING VOLUME PER UNIT OF LENGTH EQUAL TO THE INTERNAL BLOOD CONTAINING VOLUME PER THE SAME UNIT OF LENGTH OF THE BLOOD TUBE OF THE OXYGENATOR WITHIN WHICH SAID BLOOD CONDUIT PORTION IS COUPLED AND HAVING AN INTERNAL SURFACE PER THE SAME UNIT OF LENGTH AND OVER WHICH THE BLOOD PASES THERETHROUGH SUBSTANTIALLY GREATER IN AREA THAN THE INTERNAL SURFACE PER THE SAME UNIT OF LENGTH OF THE BLOOD TUBE OVER WHICH THE BLOOD PASSES AND WITHIN WHICH SAID BLOOD CONDUIT IS COUPLED
 4. IN AN OXYGENATOR HAVING A BLOOD TUBE ADAPTED TO BE CONNECTED WITH A PATIENT TO ESTABLISH BLOOD COMMUNICATION BETWEEN THE OXYGENATOR AND THE PATIENT, A THERMOSTABILIZER HAVING A BLOOD CONDUIT PORTION AND A HEAT EXCHANGE PORTION, SAID HEAT EXCHANGE PORTION SURROUNDING THE BLOOD CONDUIT PORTION TO CONTROL THE TEMPERATURE OF THE BLOOD PASSING THERETHROUGH, SAID BLOOD CONDUIT PORTION COUPLED AT OPPOSITE ENDS WITHIN SAID BLOOD TYBE TO FORM A BLOOD COMMUNICATING PORTION OF SAID TUBE, SAID BLOOD CONDUIT HAVING AN INTERNAL BLOOD CONTAINING VOLUME PER UNIT OF LENGTH EQUAL TO THE INTERNAL BLOOD CONTAINING VOLUME PER THE SAME UNIT OF LENGTH OF THE BLOOD TUBE WITHIN WHICH THE BLOOD CONDUIT IS COUPLED, SAID BLOOD CONDUIT PORTION BEING REMOVABLY REPLACEABLE WITHIN THE SURROUNDING HEAT EXCHANGE PORTION OF THE THERMOSTABILIZER WHEREBY IT MAY BE REMOVED THEREFROM AND ANOTHER BLOOD CONDUIT PORTION INSERTED THEREIN. 